The command "access-list 1 permit 160.0.0.0 0.255.255.255" permits
160.0.0.0/8, 160.0.0.0/9, 160.0.0.0/10 and so on. In order to restrict
the
update to only 160.0.0.0/8, we have to use an extended access-list of the
following format: "access-list 101 permit ip 160.0.0.0 0.255.255.255
255.0.0.0 0.0.0.0" This list permits 160.0.0.0/8 only.

I must be missing something here, because I don't see how the destination

of

255.0.0.0 with a mask of 0.0.0.0 would permit all the other 160.0.0.0
networks that had a mask different from 8.